The present invention relates generally to filters for fluid filtration.
A filter is typically provided in a fluid system to remove particulate and other contaminants before the fluid reaches a sensitive component, such as a combustion chamber, pump, compressor, etc. Many times the filter incorporates an element that is replaceable, such that a spent element can be replaced with a fresh element. The operator can either remember to change the element after, e.g., a certain number of operating hours or miles (in the case of an automobile); and/or electronic and mechanical sensors can be provided to visually or audibly notify an operator of the need for a filter change.
Examples of mechanical indicators for filters are shown in U.S. Pat. Nos. 3,068,831 and 3,812,816. In these references, a button is slideably received in a body. The body has an internal chamber that is open to the clean (downstream) side of the element. The button is normally spring-biased into an outward (clean element) position which can be confirmed by visually inspecting the button. When the media becomes clogged, the pressure on the downstream side of the element decreases as the system attempts to pull fluid through the filter. When the pressure decreases above the force of the spring (which can be appropriately chosen), the button is pulled inwardly into the body. The difference in the button position can alert the operator to an element change. The button and/or body can also incorporate colors, which visually change as the button is retracted to facilitate identifying the need for an element change. A clip, tab or other device on the button can engage the body to maintain the button in its retracted position when the engine or fluid system is shut-down to facilitate confirming the location of the button. The button can then be reset when the element is changed.
The mechanical indicator can be located at a number of different locations on the housing. One common location is in the cover of the canister. The indicator, however, must share space with other devices mounted to the cover. With a trend toward smaller filters, space can be at a premium in many applications. In addition, some covers are attached to the filter canister by a T-handle (see, e.g., U.S. Pat. No. 3,493,110). The T-handle has a threaded portion that extends through an opening in the cover and screws down into a central tubular member or standpipe projecting from the opposite end of the canister. Such a T-handle allows easy attachment and removal of a cover, but limits the ability to mount other devices on the cover, as the outwardly-projecting handle must be free from obstruction in order to grasp and rotate the handle.
U.S. Pat. No. 3,493,110 shows a mechanical indicator and a T-handle located on the cover of a filter. The indicator has a rotating pointer and is mounted separately from the handle. While the indicator has a low profile such that the handle can be rotated, Applicants believe the operator""s hand can still encounter the indicator if the operator is not careful, and it can be burdensome and somewhat uncomfortable to rotate the handle to remove and attach the cover.
Applicants believe most mechanical indicators have heretofore been a component separate from the T-handle. One reason may be that the mechanical indicator has included complex, somewhat fragile components which are necessary to provide accurate and repeatable sensing of pressure. Such components typically cannot withstand abuse or repeated handling. The handle, on the other hand, must be a robust component able to withstand repeated grasping and turning by the operator. It is believed these contrasting requirements have necessitated mounting the indicator separately from the handle.
Applicants thereby believe there is a demand for an improved mechanical indicator, particularly useful with filters incorporating T-handles, which overcomes many, if not all, of the drawbacks noted above.
The present invention provides an improved mechanical indicator for a filter, which conserves space on the cover for the filter, and which does not interfere with the operation of a T-handle.
According to the present invention, the mechanical indicator is incorporated into the T-handle as an integral indicator handle assembly. The indicator handle assembly includes a body with a handle portion and a mechanical indicator portion. The handle portion has a threaded collar that can be inserted through an opening in the cover and screwed down into a central standpipe in the filter. The handle portion further includes a handle rod supported transversely in the body to facilitate grasping and turning the indicator handle assembly.
The mechanical indicator portion of the assembly includes a button that is normally spring-biased outwardly in the body to provide a visual indication that the element is fresh. The button is located in a central chamber of the body that is open to the downstream side of the filter element. When the element becomes spent during operation of the fluid system, the pressure on the downstream side of the element drops, which causes the button to move inwardly in the body against the spring. A pair of clips engage the indicator body as the button is retracted to retain the button in the inward (spent element) position. When the indicator handle assembly is unscrewed from the canister and removed during an element change, the clips can be squeezed together to allow the indicator button to move back to its normal (fresh element) position.
A transparent cap is provided on the indicator body. The button can have a colored end that is visible through the cap to facilitate confirming the position of the button.
The integral T-handle and mechanical indicator is robust and strong, and able to withstand repeated use. The assembly uses only few components, which minimize assembly time and effort, and which prolong the useful life of the handle indicator. Preferably the indicator button includes an axially elongated slot extending radially through the button, and the body includes a corresponding pair of circular openings on opposite sides of the slot. The handle rod projects through the openings in the body and through the slot in the button, and is retained in the openings such as by press-fit. The button is constrained by the movement of the rod in the slot as the button moves axially within the body. The handle rod thereby serves the dual function of i) rotating the indicator handle assembly, and ii) locating and guiding the indicator button.
During assembly, a bias spring and wiper seal are first inserted through the upper open end the indicator body. A retainer cup can be provided to support the wiper seal. The button is then located in the body, with the clips of the button projecting downwardly into the threaded collar. The handle rod is then inserted radially through the openings in the indicator body, and through the slot in the button. The cap is then attached to the upper end of on the body to enclose the button, spring and wiper seal. The indicator handle assembly of the present invention is thereby easy to assemble, as well as to disassemble for inspection and repair.
Thus, the integral indicator handle assembly combines the usefulness of a T-handle to allow attachment of a cover to a filter canister, with a mechanical indicator to provide an indication of when a filter element needs to be replaced. The device is robust and strong, and capable of long-term use.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.